Impaction is one of the most serious issues that all reptiles might face, and can be deadly if left untreated. But it is fully avoidable, if you pick the right substrate. The biggest no-nos to avoid are woodchips, calcium sand, and reptile carpets, which are all bad for different reasons. You should also be careful not to use any unwashed substrate in your pet’s vivarium. For all our substrate tips, check out our full write-up.